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EIGRP Practice Questions

15 original questions covering ENARSI 1.9.a to 1.9.f. Answer every one before opening any explanation. Target: 12 of 15 (80%). These do not repeat the Blueprint 1.9 questions in the question bank, so do both sets.

1. Blueprint 1.9.f

A route crosses the following interfaces from the destination LAN to R1: the remote router's GigabitEthernet LAN interface, a serial T1 interface (1544 kbps, 20,000 usec) on the next router, and R1's GigabitEthernet interface. All K values are default and classic metrics are used. What metric does R1 calculate?

  • A. 2,170,112
  • B. 2,170,368
  • C. 6,476
  • D. 512,512
Answer: B

The minimum bandwidth is 1544 kbps, and 10,000,000 / 1544 truncates to 6476. The delays are 10 + 20,000 + 10 = 20,020 usec, which is 2002 tens of microseconds. 256 x (6476 + 2002) = 2,170,368. A is the reported distance of the router with the serial interface (it does not include R1's own Gi delay). C is only the bandwidth term without delay and without the 256 multiplier.

2. Blueprint 1.9.f

Refer to the exhibit. R1 runs EIGRP named mode with default settings. What value does R1 show for this route in show ip route?

R1# show ip eigrp topology 10.30.30.0/24 | include FD|Composite
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2621440, RIB is ?
      Composite metric is (2621440/1310720), route is Internal
  • A. 2,621,440
  • B. 10,240
  • C. 40,960
  • D. 20,480
Answer: D

Named mode divides the 64-bit composite metric by the metric rib-scale, which defaults to 128, before installing it. 2,621,440 / 128 = 20,480. B is the RD divided by 128. A would only appear with a rib-scale of 1. The value is 65,536 x (10 + 30), a route three Gigabit interface delays away.

3. Blueprint 1.9.e

R1 has a successor with FD 131,072 and a feasible successor with a computed distance of 300,000. What is the lowest variance value that installs both paths?

  • A. 2
  • B. 3
  • C. 128
  • D. 4
Answer: B

A path is installed when its metric is less than variance x FD. With variance 2, the limit is 262,144, which is below 300,000. With variance 3, the limit is 393,216, which is above it. 128 is the maximum variance and would work, but it is not the lowest value.

4. Blueprint 1.9.b

Refer to the exhibit. R1 and R2 keep losing their adjacency. Which change fixes the problem?

R1# show logging | include DUAL
%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.2.2 (GigabitEthernet0/1) is down: holding time expired
%DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.2.2 (GigabitEthernet0/1) is up: new adjacency

R2# show running-config | section af-interface GigabitEthernet0/1
  af-interface GigabitEthernet0/1
   hello-interval 30
  exit-af-interface
  • A. Configure hello-interval 30 on R1 so the timers match
  • B. Configure hold-time 90 on R1
  • C. Configure hold-time 90 under the same af-interface on R2
  • D. Remove hello-interval from R1
Answer: C

Each router advertises its own hold time in its hellos. R2 sends hellos every 30 seconds but still advertises the default hold time of 15, so R1 gives up on R2 between hellos. Raising R2's hold time to three times its hello fixes it. Matching R1's hello (A) does not change what R2 advertises, and EIGRP does not require matching timers. R1's hold time (B) only controls how long R2 waits for R1.

5. Blueprint 1.9.b

Which configuration enables HMAC-SHA-256 authentication for EIGRP on GigabitEthernet0/1?

  • A. interface Gi0/1 then ip authentication mode eigrp 100 hmac-sha-256 S3cret
  • B. router eigrp CORP, address-family ipv4 unicast autonomous-system 100, af-interface Gi0/1, authentication mode hmac-sha-256 0 S3cret
  • C. router eigrp 100 then authentication mode hmac-sha-256 0 S3cret
  • D. key chain K with cryptographic-algorithm hmac-sha-256, then ip authentication key-chain eigrp 100 K on the interface
Answer: B

HMAC-SHA-256 for EIGRP is a named-mode feature configured under af-interface (or af-interface default). Classic mode supports MD5 only, so A and C do not exist in classic mode. D describes a key-chain algorithm option that is not how EIGRP classic mode authentication is enabled.

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